JP2014000824A - Multilayered material sheet and process for its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for preparing a multilayered material sheet, and a ballistic resistant article including the multilayered material sheet.SOLUTION: The invention relates to a multilayered material sheet comprising a consolidated stack of unidirectional monolayers of a drawn polymer, where the drawing directions of two subsequent monolayers in the stack are different. At least one monolayer comprises a plurality of unidirectional tapes of the drawn polymer aligned in the same direction, each tape having longitudinal edges not overlapping the adjacent tapes, the monolayer including a binder. For a ballistic resistant article, the polymer is selected from the group consisting of polyolefins, polyesters, polyvinyl alcohols, polyacrylonitriles, polyamides, liquid crystalline polymers and ladder-like polymers, where the polyolefins include ultra high molecular weight polyethylenes. The ballistic resistant article includes further a sheet of an inorganic material selected from the group consisting of ceramic, steel, aluminum, magnesium, titanium, nickel, chromium and iron or their alloys, glass and graphite, or combinations thereof.

Description

Detailed Description of the Invention

  The present invention relates to a multilayer material sheet comprising a unidirectional monolayer consolidated stack of stretched polymers and a method for its preparation. The present invention also relates to an elastic resistant article including the multilayer material sheet.

  A multilayer material sheet comprising a consolidated stack of unidirectional monolayers of stretched polymer is known from EP 1627719 A1. This publication discloses a multilayer material sheet comprising a plurality of unidirectional monolayers of ultra-high molecular weight polyethylene, essentially free of a bonding matrix, and the orientation direction of two consecutive monolayers in the stack Is different. A single layer of multilayer material disclosed in EP 1627719 A1 is produced by positioning a plurality of ultra high molecular weight polyethylene tapes adjacent to each other, the adjacent positioned tapes being along their side edges. At least partially overlap. Known multilayer materials cannot be produced without overlap. Also, in order to obtain good ballistic properties, the material sheet of EP 1627719 A1 essentially does not have a binding matrix and exclusively uses ultra high molecular weight polyethylene.

  The multilayer material sheet according to EP 1627719 A1 shows satisfactory ballistic performance, but this performance can be further improved.

  It is an object of the present invention to provide a multilayer material sheet that has at least the same ballistic properties as known materials and can be easily manufactured.

  This object is achieved according to the present invention by providing a multilayer material sheet comprising a unidirectional single layer consolidated stack of stretched polymers, the stretch directions of two consecutive monolayers in the stack being different and at least 1 One single layer includes at least one stretched polymer unidirectional tape, each tape including a longitudinal edge, the single layer overlapping adjacent to and along a substantial length of the longitudinal edge. There are no or increased areas of thickness. Preferably, the monolayer overlaps adjacent to and along at least 50%, 60%, 70%, 80%, 90% or 95% of the length of the longitudinal edge of the at least one unidirectional tape. There are no or increased areas of thickness. More preferably, the monolayer has no overlap or no increased thickness area along and adjacent to the entire length of the longitudinal edge of the at least one unidirectional tape.

  The formation of a single layer without overlapping or excessive levels of binder allows the single layers to be more easily stacked and compressed into a multilayer material sheet having a uniform areal density and more over the entire area of the multilayer material sheet. Homogeneous bulletproof performance can be obtained.

  In one embodiment of the present invention, this object is achieved by a multilayer material sheet comprising a unidirectional single-layer consolidated stack of stretched polymers and a method of manufacturing the multilayer material sheet, wherein two successive layers in the stack The stretching directions of the single layers are different, and at least one single layer includes a plurality of stretched polymer unidirectional tapes aligned in the same direction, and adjacent tapes do not overlap.

  Multilayer material sheets according to the invention, i.e. extensively bonded with and along the longitudinal edge of a unidirectional tape, with increased thickness areas, e.g. longitudinal tape overlap, or overlapping bonding materials It can be seen that a sheet that is substantially free of tape not only improves the ballistic properties of the sheet, but also unexpectedly improves it. Preferably, the monolayer does not include an increased thickness region extending along (but not transverse to) the longitudinal edge of at least one unidirectional tape and adjacent thereto. The occurrence of increased thickness regions extending along and adjacent to the longitudinal edge of the unidirectional tape is one such as observed when the tape is aligned to form a woven structure. It is more difficult to form a homogeneous consolidated stack compared to the increased thickness region due to the transverse overlap of directional tapes.

  A particularly preferred multilayer material sheet according to the present invention comprises a stack of single layers, each single layer being composed of unidirectional tapes of a plurality of stretched polymers aligned in the same direction, with adjacent tapes in each single layer overlapping. Do not fit. The material sheet according to the invention is more homogeneous than the known material sheet. In fact, at the location of overlap, the known material sheets can have zones of increased areal density. These zones are not present in the material sheet of the present invention or are less likely to occur. This feature surprisingly improves the ballistic properties.

  A single layer of the multilayer material sheet of the present invention is preferably produced by positioning a plurality of tapes with the longitudinal edges of the tapes as close as possible to each other and preferably in close contact. However, it would be desirable to allow gaps between adjacent tapes (ie, adjacent tapes within a single layer have their longitudinal length to allow for the production of single layers on an industrial scale at an economical rate. No contact along directional edge-gap greater than 0%). Preferably, the material sheet according to the present invention is such that the gap between adjacent tapes in a single layer is less than 10% of the width of adjacent unidirectional tapes, even more preferably less than 5%, and even more preferably. Is less than 3% of the width of adjacent unidirectional tapes. Most preferably, the gap between adjacent tapes in a single layer is less than 1%.

  The material sheet according to this preferred embodiment is easily manufactured and still exhibits the same level of ballistic properties as the material sheet without gaps. A single layer according to the invention is preferably produced by positioning a plurality of tapes such that their longitudinal edges touch each other, but with only one (sufficiently wide) tape having a sufficient width. Constructed monolayers are also included within the scope of the present invention. This is because such a single layer does not exhibit increased thickness areas along and adjacent to the length of the longitudinal edge of at least one unidirectional tape.

  More than known materials by aligning multiple stretched polymer tapes so that each tape is oriented parallel to the adjacent tape and a substantial amount of adjacent tape, i.e., at least 90% do not overlap. Improved bulletproof performance is achieved. According to the prior art, as described in EP 1627719 A1, a unidirectional monolayer comprises a plurality of high-strength unidirectional polyethylene tapes oriented in parallel in a plane but partially overlapping. The overlapping region has a width of about 5 mm to 40 mm. According to an alternative embodiment, a narrow polymer film with a width of about 5-20 mm is placed on the contact area between two adjacent tapes. An additional advantage of the multilayer material sheet of the preferred embodiment of the present invention is that no such additional polymer film is required to obtain good ballistic properties. In addition, by having a tape that does not contain areas of increased thickness as defined in the present invention, stacking and consolidating single layers sequentially under pressure results in a more homogeneous multilayer material sheet compared to the prior art. Will obtain a good areal density or thickness.

  A particularly preferred embodiment of the multilayer material sheet according to the invention is that the polymer from which the sheet is made is a polyolefin, polyester, polyvinyl alcohol, polyacrylonitrile, polyamide, in particular poly (p-phenylene terephthalamide), a liquid crystal polymer and a ladder polymer, for example Such as polybenzimidazole or polybenzoxazole, in particular poly (1,4-phenylene-2,6-benzobisoxazole), or poly (2,6-diimidazo [4,5-b-4 ′, 5′-e] It is selected from the group consisting of pyridinylene-1,4- (2,5-dihydroxy) phenylene). Unidirectional tapes and monolayers from these polymers are preferably highly oriented by stretching the material form, eg, film, at an appropriate temperature. Unidirectional tapes and monolayers in the context of this application mean tapes and monolayers that exhibit a preferred orientation of the polymer chains in one direction, ie the stretch direction. Such tapes and monolayers can be produced by stretching, preferably uniaxial stretching, and will exhibit anisotropic mechanical properties.

  The multilayer material sheet of the present invention allows the use of stretched polymers having a relatively low strength, and therefore does not require ultra high molecular weight polyethylene to obtain good ballistic performance. However, its preferred embodiment comprises ultra high molecular weight polyethylene. The ultra high molecular weight polyethylene may be linear or branched, but preferably linear polyethylene is used. Linear polyethylene is understood herein to mean a polyethylene having less than one side chain per 100 carbon atoms, preferably less than one side chain per 300 carbon atoms. Or the branch usually contains at least 10 carbon atoms. For example, as described in EP 0269151, the side chain can be appropriately measured by FTIR in a 2 mm thick compression molded film. The linear polyethylene can further contain up to 5 mol% of one or more other alkenes that can be copolymerized, such as propene, butene, pentene, 4-methylpentene, octene. Preferably, the linear polyethylene has a high molar mass and the intrinsic viscosity (IV, measured with decalin solution at 135 ° C.) is at least 4 dl / g, more preferably at least 8 dl / g, most preferably at least 10 dl / g. . Such polyethylene is also called ultra high molecular weight polyethylene. Intrinsic viscosity is a measure of molecular weight that can be more easily determined than actual molar mass parameters such as Mn and Mw. This type of polyethylene film provides particularly good ballistic properties.

  The tape according to the invention can be prepared in the form of a film. A preferred method of forming such a film or tape is to supply the polymer powder during the endless belt combination, compress the polymer powder at a temperature below its melting point, and roll the resulting compression molded polymer. Followed by stretching. Such a method is described, for example, in EP 0 733 460 A2, which is incorporated herein by reference. If desired, prior to feeding and compression molding the polymer powder, the polymer powder may be mixed with a suitable liquid organic compound having a boiling point higher than the melting point of the polymer. Compression molding may be performed by temporarily holding the polymer powder between the endless belts while conveying the endless belts. This can be done, for example, by providing a pressure platen and / or roller connected to an endless belt. The UHMWPE polymer used in this method is required to be stretchable in the solid state.

  Another preferred method of forming the film involves feeding the polymer to an extruder, extruding the film at a temperature above its melting point, and stretching the extruded polymer film. If desired, the polymer may be mixed with a suitable liquid organic compound, for example to form a gel, such as when using ultra high molecular weight polyethylene, preferably before feeding the polymer to the extruder. .

  Stretching of the produced film, preferably uniaxial stretching, can be performed by means known in the art. Such means include extrusion stretching and tensile stretching in suitable stretching equipment. Stretching may be performed in multiple stages to achieve increased mechanical strength and stiffness. For the preferred ultra high molecular weight polyethylene film, stretching is usually performed uniaxially in a number of stretching steps. The first stretching step can include, for example, stretching up to an elongation factor of 3. Multiple stretches typically yield an elongation factor of 9 at stretch temperatures up to 120 ° C., an elongation factor of 25 at stretch temperatures up to 140 ° C., and an elongation factor of 50 at stretch temperatures up to 150 ° C. and higher. By multiple stretching at increasing temperatures, an elongation factor of about 50 or more can be achieved. As a result, a high-strength tape is obtained, whereby a strength of 1.5 GPa to 1.8 GPa or more can be obtained in the case of an ultra-high molecular weight polyethylene tape.

The resulting stretched tape may itself be used to produce a single layer, or it may be cut to its desired width or divided along the stretch direction. Preferably, the single layer is made from a continuous tape. The width of the unidirectional tape thus produced is only limited by the width of the film from which the tape is produced. The width of the tape is preferably greater than 2 mm, more preferably greater than 5 mm, and most preferably greater than 30 mm. The areal density of the tapes or single layer over a wide range may vary for instance between 5 to 200 g / ^{m 2.} Preferred areal density is between 10~120g / ^{m 2,} more preferably between 15 to 80 g / ^{m 2,} and most preferably between 20 to 60 g / ^{m 2.}

  Another particularly preferred multilayer material sheet according to the present invention comprises at least one monolayer, preferably all monolayers, composed of unidirectional tapes of a plurality of stretched polymers aligned to form a woven structure. Including. Such tapes can be produced by applying textile techniques such as weaving, knitting, etc. instead of fibers (usually done in fibers) of small strips of drawn polymer. In this embodiment, the polymer strip has an increased thickness area where the strips partially overlap at the intersection, but the increased thickness area does not extend along and adjacent to the longitudinal edge. Rather, traverse the longitudinal edge of the unidirectional tape. Each tape (small strip of woven fabric) is positioned so that there is no overlap between adjacent tapes aligned in the same direction. The ballistic properties are further improved by stacking the tapes so that the seam lines in different single layers are staggered with respect to each other.

  In some embodiments, the single layer is applied locally to bond and stabilize multiple unidirectional tapes so that the single layer structure is maintained during handling and manufacturing of the unidirectional sheet. Can be included. Suitable binders are described, for example, in EP0191306B1, EP1170925A1, EP0683374B1 and EP1144740A1. The binder can be applied in a variety of forms and methods, for example, transverse binding strips (transverse with respect to the unidirectional tape). The application of the binder during the formation of a single layer advantageously stabilizes the tape, thus allowing for faster production cycles to be achieved while avoiding overlap between adjacent tapes.

  In one embodiment, the binder is applied such that adjacent unidirectional tapes abut against each other along their longitudinal edges. Since the role of the binder is to temporarily hold and stabilize multiple unidirectional tapes during handling and manufacture of the unidirectional sheet, local application of the binder is preferred. The topical application of the binder is an application limited to the immediate vicinity of the longitudinal edge and may include intermittent topical application (spot application along the longitudinal edge).

  Preferably, the application of the binder results in a maximum increase in monolayer thickness (raised edge) that is 150% of the average thickness of the unidirectional tape forming the monolayer. More preferably, the application of the binder results in a maximum increase in thickness that is 120%, 110% or 105% of the average thickness of a plurality of unidirectional tapes forming a single layer. In another embodiment, the application of the binder results in an increase in the thickness of the monolayer adjacent to the longitudinal edge of the unidirectional tape that is less than 4 microns, more preferably less than 3, 2 or 1 micron. .

  In embodiments involving intermittent topical application of the binder, the percentage of the longitudinal edge comprising the binder is preferably less than 50%, 30%, 20%, 10%, 5% or 2%. Similarly, the percentage of the longitudinal edge (or area adjacent to the longitudinal edge) of the unidirectional tape that is increased due to the application of the binder is preferably 50%, 30%, 20%, 10% Less than 5% or 2%. Preferably, the binder comprises less than 20%, 10%, 5%, 2%, 1%, 0.5%, or 0.2% of the weight of the single layer or consolidated stack.

  In an alternative embodiment, a coupling means such as ultrasonic welding may be used to intermittently fuse together the longitudinal edge portions of adjacent unidirectional tapes.

  When adjacent unidirectional tapes in a single layer are joined intermittently along adjacent longitudinal edges, the adjacent unidirectional tapes are held in a parallel array. The application of the binder allows adjacent unidirectional tapes to be in close proximity without substantial overlap of adjacent longitudinal edges. Local variations in monolayer thickness are advantageously reduced (compared to conventional monolayers where longitudinal edges overlap or polymer bonded strips overlap continuously), resulting in more Contributes to a single-layer consolidated stack having a uniform thickness and thus a stress distribution.

  The thickness of the single layer or the tape of the multilayer material sheet can in principle be selected within a wide range. Preferably, however, the multilayer material sheet according to the invention is characterized in that the thickness of the at least one monolayer does not exceed 120 μm, more preferably does not exceed 50 μm and most preferably is between 5 and 29 μm. . Particularly good ballistic properties are achieved if the thickness of all monolayers of the stack does not exceed 120 μm, more preferably does not exceed 50 μm, and most preferably is between 3 and 29 μm. Further preferred multilayer material sheets according to the invention are characterized in that the thickness of at least one monolayer is greater than 10 μm and does not exceed 50 μm, preferably does not exceed 100 μm or more preferably does not exceed 120 μm. .

  By limiting the thickness of at least one monolayer in the stack to the claimed thickness, surprisingly sufficient ballistic properties are achieved even if the monolayer has a fairly limited strength.

  The strength of the tape in the multilayer material sheet is highly dependent on the polymer from which the tape is made and its (uniaxial) stretch ratio. The strength of the tape (and monolayer) is at least 0.75 GPa, preferably at least 0.9 GPa, more preferably at least 1.2 GPa, even more preferably at least 1.5 GPa, even more preferably at least 1.8 GPa, and even more Preferably it is at least 2.1 GPa, and most preferably at least 3 GPa. The unidirectional monolayers are preferably sufficiently interconnected with each other, meaning that the unidirectional monolayers do not delaminate under normal use conditions such as room temperature.

  The multilayer material sheet according to the present invention preferably has at least 2 unidirectional monolayers, preferably at least 4 unidirectional monolayers, more preferably at least 6 unidirectional monolayers, even more preferably at least 8 It includes directional monolayers, and most preferably at least 10 unidirectional monolayers. Increasing the number of unidirectional monolayers in the multilayer material sheets of the present invention simplifies the manufacture of articles (eg, bulletproof plates) from these material sheets.

In one embodiment of the invention,
(A) positioning a first at least one stretched polymer unidirectional tape on a moving substrate, thereby forming a first monolayer, the longitudinal direction of the at least one unidirectional tape; Adjacent to and along the substantial length of the edge, the monolayer does not include an area of increased thickness;
(B) holding the first monolayer on the moving substrate;
(C) positioning a second at least one stretched polymer unidirectional tape on the first monolayer, thereby forming a second monolayer, wherein the direction of the second monolayer is Forming an angle α with respect to the direction of the first monolayer;
(D) compressing the stack thus formed to consolidate the monolayer, a method of preparing a multilayer material sheet is provided. The single layer consolidated stack is preferably because there is reduced or no increased thickness area along and adjacent to the longitudinal edge of at least one unidirectional tape in each of the single layers. It has a more uniform thickness / area density compared to the prior art.

In a preferred embodiment of the present invention, a method for preparing a multilayer material sheet of the claimed type is provided. The method according to the invention comprises:
(A) providing a plurality of stretched polymer tapes aligned such that each tape is oriented parallel to an adjacent tape, the adjacent tapes being substantially non-overlapping;
(B) positioning a plurality of stretched polymer tapes on the moving substrate, thereby forming a first monolayer;
(C) holding the first monolayer on the moving substrate;
(D) positioning a plurality of stretched polymer tapes on the first monolayer, thereby forming a second monolayer, wherein the direction of the second monolayer is in the direction of the first monolayer A step of forming an angle α with respect to
(E) compressing the stack thus formed to consolidate the monolayer. Step (a) can optionally include the application of a binder or bonding means to hold or stabilize adjacent tapes so that increased production rates can be achieved. Using the claimed method, a multi-layer material sheet can be readily produced that is substantially free of overlapping regions, i.e., areas of increased areal density. The material sheets thus produced have improved ballistic properties with respect to material sheets having overlapping areas.

  Preferably, the plurality of stretched polymer tapes are unwound from the rewind station, and step (d) is performed by folding the plurality of stretched polymer tapes at least partially on itself. More preferably, the plurality of stretched polymer tapes are positioned such that the first monolayer forms an angle β with respect to the direction of substrate movement, and the fold extends substantially parallel to the direction of movement of the substrate. To be done. The method according to the invention is further characterized in that the angle β is between 40 and 50 degrees, most preferably the angle β is about 45 degrees.

  Another preferred method according to the invention is characterized in that the second monolayer is at least partly bonded to the first monolayer. This can be easily accomplished, for example, by ultrasonic welding, the addition of a low melting film, an adhesive, or any other method of bonding layers together. The adhesion of the second monolayer to the first monolayer is preferably sufficient to allow transport of the monolayer assembly without substantial relative movement of another tape and / or monolayer. Powerful.

  According to the method of the present invention, a multilayer material sheet is produced in which the stretching directions of two consecutive monolayers in the stack differ by an angle α. For the preferred method in which the crease extends approximately parallel to the direction of movement of the substrate, the angle α = 2β. Although the angle α can be selected within a wide range, the angle α is preferably between 45 and 135 °, more preferably between 65 and 115 °, and most preferably between 80 and 100 °. It is. In the latter preferred range, a particularly preferred angle α is about 90 °. The material produced according to this preferred embodiment is indicated in the art as a cross-ply.

  The multilayer material sheet according to the invention is particularly useful in the production of ballistic resistant articles such as vests or armor plates. Ballistic applications include applications that have ballistic threats to several types of projectiles, including so-called AP bullets and hard particles (eg, debris and shrapnel) that penetrate bulletproof objects.

  The ballistic resistant article according to the invention comprises at least two unidirectional monolayers, preferably at least 10 unidirectional monolayers, more preferably at least 20 unidirectional monolayers, even more preferably at least 30 unidirectional. Single layers, and most preferably at least 40 unidirectional monolayers. The stretching direction of two consecutive monolayers in the stack differs by an angle α. The angle α is preferably between 45 and 135 °, more preferably between 65 and 115 °, and most preferably between 80 and 100 °.

  Preferably, the ballistic resistant article according to the present invention is selected from the group consisting of ceramic, metal (preferably aluminum, magnesium, titanium, nickel, chromium and iron) or alloys thereof, glass, graphite, or combinations thereof. Including additional sheets of inorganic material. Particularly preferred is a metal. In such cases, the metal in the metal sheet preferably has a melting point of at least 350 ° C, more preferably at least 500 ° C, and most preferably at least 600 ° C. Suitable metals include aluminum, magnesium, titanium, copper, nickel, chromium, beryllium, iron and copper, such as steel and stainless steel and alloys of aluminum and magnesium (so-called aluminum 5000 series), and aluminum and zinc. And alloys thereof such as magnesium or alloys with zinc, magnesium and copper (so-called aluminum 7000 series). In the alloy, for example, the amount of aluminum, magnesium, titanium and iron is preferably at least 50% by weight. Preferred metal sheets include aluminum, magnesium, titanium, nickel, chromium, beryllium, iron (including these alloys). More preferably, the metal sheet is based on aluminum, magnesium, titanium, nickel, chromium, iron and alloys thereof. This results in a light weight ballistic article with good durability. Even more preferably, the iron and its alloys in the metal sheet have a Brinell hardness of at least 500. Most preferably, the metal sheet is based on aluminum, magnesium, titanium, and alloys thereof. This results in the lightest ballistic resistant article with the highest durability. Durability in this application refers to the lifetime of the composite under conditions exposed to heat, moisture, light and ultraviolet radiation. Although the further material sheet can be positioned anywhere in the single layer stack, the preferred resilient article is characterized in that the additional material sheet is positioned outside the single layer stack, most preferably at least on its impingement surface. .

  The ballistic resistant article according to the invention preferably comprises a further sheet of the above-mentioned inorganic material having a thickness of at most 100 mm. Preferably, the maximum thickness of the further sheet of inorganic material is 75 mm, more preferably 50 mm, and most preferably 25 mm. This results in the best balance between weight and ballistic properties. Preferably, when the further sheet of inorganic material is a metal sheet, the thickness of the metal sheet is at least 0.25 mm, more preferably at least 0.5 mm, and most preferably at least 0.75 mm. As a result, even better bulletproof performance can be obtained.

  Additional sheets of inorganic material may optionally be pretreated to improve adhesion with the multilayer material sheet. Appropriate pretreatment of the further sheets includes mechanical treatment, such as roughening or cleaning of its surface by polishing or grinding, for example chemical etching with nitric acid, and lamination with polyethylene film.

  In another embodiment of the ballistic resistant article, a tie layer, such as an adhesive, may be applied between the further sheet and the multilayer material sheet. Such adhesives can include epoxy resins, polyester resins, polyurethane resins, or vinyl ester resins. In another preferred embodiment, the tie layer can further comprise a woven or non-woven layer of inorganic fibers, such as glass fibers or carbon fibers. It is also possible to attach further sheets to the multilayer material sheet by mechanical means such as screws, bolts and snap fits. If the ballistic resistant article according to the invention is used in ballistic applications where a threat to AP bullets, fragments or simple explosives can be encountered, the further sheet preferably comprises a metal sheet coated with a ceramic layer. In this way, the following layered structure: ceramic layer / metal sheet / at least two unidirectional sheets (the direction of the fibers of the unidirectional sheet is at an angle α to the direction of the fibers of the adjacent unidirectional sheet There is obtained an anti-ballistic article. Suitable ceramic materials include, for example, alumina oxide, titanium oxide, silicon oxide, silicon carbide and boron carbide. The thickness of the ceramic layer depends on the level of ballistic threat but usually varies between 2 mm and 30 mm. This ballistic resistant article is preferably positioned so that the ceramic layer faces a ballistic threat.

In one embodiment of the invention,
(A) stacking at least two unidirectionally stretched polymer monolayers and sheets of material selected from the group consisting of ceramic, steel, aluminum, titanium, glass and graphite, or combinations thereof, each A single layer includes at least one unidirectional tape, two continuous single layers in a stack have different stretching directions, and are adjacent to a substantial length of a longitudinal edge of at least one unidirectional tape. And along which, at least one monolayer does not include an area of increased thickness;
(B) A method for producing an elastic-resistant article including the step of consolidating the stacked sheets by applying temperature and pressure.

In a preferred embodiment of the present invention,
(A) stacking at least two unidirectionally stretched polymer monolayers and further sheets of inorganic material selected from the group consisting of ceramic, steel, aluminum, titanium, glass and graphite, or combinations thereof, , Two continuous monolayers in the stack have different stretch directions, at least one monolayer, and preferably all monolayers comprise unidirectional tapes of a plurality of stretched polymers aligned in the same direction; A step where adjacent tapes do not overlap;
(B) A method for producing an elastic-resistant article including the step of consolidating the stacked sheets by applying temperature and pressure.

  In an alternative method, a stack of at least two unidirectionally oriented polymer monolayers has been produced in a separate process as described above. This prefabricated stack is then combined with a further sheet of material selected from the group consisting of ceramic, steel, aluminum, titanium, glass and graphite, or combinations thereof in step (a) of the method. The

  Consolidation of all the above methods can be suitably performed in a hydraulic press. Consolidation is intended to mean that the monolayers are relatively firmly attached to each other to form a unit. The temperature during consolidation is usually controlled by the temperature of the press. The minimum temperature is usually selected to obtain a reasonable rate of consolidation. In this regard, 80 ° C. is a suitable lower temperature, preferably the lower limit is at least 100 ° C., more preferably at least 120 ° C., and most preferably at least 140 ° C. The maximum temperature is selected below the temperature at which the stretched polymer monolayer loses its high mechanical properties, for example due to melting. Preferably, the temperature is at least 10 ° C., preferably at least 15 ° C., and even more preferably at least 20 ° C. lower than the melting temperature of the stretched polymer monolayer. If the stretched polymer monolayer does not exhibit a clear melting temperature, the temperature at which the stretched polymer monolayer begins to lose its mechanical properties should be read instead of the melting temperature. For the preferred ultra high molecular weight polyethylene, a temperature lower than 145 ° C will usually be selected. The pressure during consolidation is preferably at least 7 MPa, more preferably at least 15 MPa, even more preferably at least 20 MPa, and most preferably at least 35 MPa. In this way, a rigid ballistic article is obtained. The optimum time for consolidation is usually in the range of 5 to 120 minutes depending on conditions such as temperature, pressure and part thickness and can be confirmed by routine experimentation. If a curved antiballistic article is produced, it may be advantageous to first pre-form additional material sheets into the desired shape and then compact with single and / or multilayer material sheets.

  Preferably, in order to achieve high resilience, cooling is performed under pressure as well after compression molding at high temperature. The pressure is preferably maintained at least until the temperature is sufficiently low to prevent relaxation. This temperature can be defined by one skilled in the art. When an elastic resistant article comprising a single layer of ultra high molecular weight polyethylene is produced, the typical compression temperature is in the range of 90-150 ° C, preferably 115-130 ° C. Typical compression pressures range from 100 to 300 bar, preferably from 100 to 180 bar, more preferably from 120 to 160 bar, and the compression time is usually between 40 and 180 minutes.

  The multilayer material sheets and ballistic resistant articles of the present invention provide at least the same level of protection as known articles at significantly lower weight, or provide improved ballistic performance at comparable weights compared to known articles, This is particularly advantageous over previously known ballistic materials. The starting materials are cheap and the manufacturing process is relatively simple and therefore cost effective. Since various polymers can be used to produce the multilayer material sheet of the present invention, properties can be optimized according to the particular application. In addition to elasticity resistance, properties include, for example, thermal stability, shelf life, deformation resistance, ability to bond to other material sheets, formability, and the like.

  The present invention will now be further illustrated by the following FIGS. 1-4 (but is not limited thereto).

  Referring to FIG. 1, an apparatus 1 for producing a multilayer material sheet of the claimed type is shown. The apparatus includes means 2 for providing a plurality of stretched polymer tapes 10. Means 2 may include a rewind station for a roll of polymer tape 10, for example. The polymer tapes 10 are aligned so that each tape 10 is oriented parallel to the adjacent tape 10. The device 1 further comprises a moving substrate 3, which in the embodiment is shown as a belt and is driven by two cylindrical rolls 4. The belt 3 can move at a speed V3 in the direction indicated by the arrow. The plurality of tapes 10 are positioned on the substrate 3 by passing the tape 10 through a set of nip rollers (5a, 5b). The plurality of tapes 10 are held on the substrate 3 by holding means, for example by providing a space 6 that can be pierced through the substrate 3 and placed under vacuum by a pump 7 below the substrate 3. Behind the movable substrate 3 is positioned a belt press 20 that includes two heating surfaces (21, 22) and is driven by a cylindrical roll 23.

  The method according to the invention comprises unwinding a plurality of uniaxially stretched polymer tapes 10 from the unwind station 2 at a speed V1. The tape 10 is positioned so that adjacent tapes do not substantially overlap, and there is substantially no gap between adjacent tapes (typically less than 2 mm). Next, the tape 10 is fed through a set of nip rollers (5a, 5b). As shown in FIG. 1, the unwinder 2 and the set of nip rollers (5a, 5b) cross the substrate 3 up and down in the transverse direction at a speed V2. The vacuum belt substrate 3 moves at a speed V3 in a direction essentially perpendicular to the transverse direction. The ratio between V2 and V3 is selected such that the plurality of tapes 10 are positioned on the moving substrate 3 at an angle of about 45 degrees with respect to the direction of movement of the substrate 3, whereby the first single layer Is formed. The first single layer is held on the moving substrate 3 by suction generated by the vacuum means (6, 7). When the rewinding machine 2 reaches the side surface of the moving substrate 3, the moving direction is reversed and the rewinding machine 2 moves in the opposite direction. Thereby, the plurality of stretched polymer tapes 10 are at least partially folded onto itself. More specifically, the plurality of stretched polymer tapes 10 are folded so that the folds extend substantially parallel to the direction of movement of the substrate 3. Thereby, the second monolayer is positioned on the first monolayer, and the direction of the second monolayer forms an angle of about 90 degrees with respect to the direction of the first monolayer. In order to ensure that the first and second monolayer assembly can be transported without relative movement of another tape and / or monolayer, the second monolayer of the tape is at least partially Bonded to a single layer. Suitable means for doing this include, but are not limited to, ultrasonic welding, application of a low melting film, adhesive, hot melt, or any other method of bonding layers together.

  Finally, the single layer assembly thus formed is fed to a belt press or calendar 20 for final consolidation of the multilayer material sheet. In the belt press or calendar 20, the stacked tapes are bonded at a temperature close to the melting point of the tape. In the described embodiment, the resulting multilayer material is a cross-ply bilayer material made from tape, and the direction of the tape is at an angle of about 45 degrees relative to the direction of movement of the substrate 3.

  The width of the plurality of tapes 10 in the means 2 is determined by the width of the multilayer material on the substrate 3 to be positioned on the belt press or calendar number 20. When the angle β between the tape and the moving direction of the substrate 3 is 45 ° C., the width of the plurality of tapes 10 is √2 * the width of the multilayer material.

  Referring to FIG. 2, there is shown a graphic representation of a multilayer material sheet according to the present invention comprising a unidirectional single layer consolidated stack of two stretched polymers, wherein the stretch direction of two consecutive single layers in the stack is Rotated 90 °, each single layer includes a plurality of stretched polymer unidirectional tapes aligned in the same direction and adjacent tapes do not overlap. For clarity, individual tapes extend at the edges of the multilayer material sheet.

  Referring to FIG. 3, there is shown a single layer graphic representation in accordance with the present invention in which a single layer is constructed from unidirectional tapes of a plurality of stretched polymers aligned to form a woven structure.

  Referring to FIG. 4, a graphic of a multilayer material sheet according to the present invention comprising the single layer of FIG. 3 indicated by the number 1 (solid line) together with the second single layer of woven tape indicated by the number 2 (dashed line) below it. The display is shown. The second single layer is positioned such that the seam lines of each single layer are staggered.

The test methods referred to in this application are as follows.
Intrinsic viscosity (IV) is a different concentration at 135 ° C. in decalin with DBPC as antioxidant in an amount of 2 g / l solution according to method PTC-179 (Hercules Inc. Rev., April 29, 1982). Is determined by extrapolating the viscosity measured at 0 to zero concentration (dissolution time is 16 hours).
Tensile properties (measured at 25 ° C.): Tensile strength (or strength), tensile modulus (or modulus) and elongation at break (or eab) are nominal gauge length of 500 mm fiber, 50% / min crosshead speed Are defined and determined in multifilament yarns as defined in ASTM D885M. Based on the measured stress-strain curve, the modulus is determined by ramping the strain between 0.3-1%. To calculate the modulus and strength, the measured tensile force is divided by the titer determined by weighing 10 meters of fiber, and the GPa value assumes a density of 0.97 g / cm ^3. Calculated. The tensile properties of the thin film were measured according to ISO 1184 (H).

1 schematically shows an embodiment of an apparatus for carrying out the method according to the invention. 1 schematically shows a multilayer material sheet. 1 schematically shows a single layer of woven tape. 1 schematically shows a multilayer material sheet.

Claims (28)

  A multilayer material sheet comprising a unidirectional single-layer consolidated stack of stretched polymers, wherein the stretch directions of two consecutive single layers in the stack are different and at least one single layer is one of at least one stretched polymer. Directional tape, each tape including a longitudinal edge, adjacent to and along a substantial length of the longitudinal edge of the at least one unidirectional tape, the monolayer being thick A multilayer material sheet that does not include an increased area, and wherein the adjacent tapes do not overlap when the single layer includes more than one unidirectional tape of the drawn polymer.   The multilayer material sheet of claim 1, wherein the at least one monolayer does not include a region of increased thickness along and adjacent the entire length of a longitudinal edge of the at least one unidirectional tape.   The multilayer material according to claim 1 or 2, wherein at least one monolayer comprises a plurality of stretched polymer unidirectional tapes and the gap between adjacent tapes is less than 10% of the width of adjacent unidirectional tapes. Sheet.   The multilayer material sheet according to claim 3, wherein a gap between the adjacent tapes is smaller than 5% of a width of the adjacent unidirectional tape.   The multilayer material sheet according to any one of claims 1 to 4, wherein longitudinal edges of the adjacent tapes at least partially abut against each other.   The multilayer material sheet of claim 5, wherein the adjacent tapes are at least partially abutted against each other.   The multilayer material sheet according to any one of the preceding claims, wherein the thickness of the at least one monolayer does not exceed 100 microns.   The multilayer material sheet of claim 7, wherein the thickness of at least one monolayer does not exceed 29 microns.   The multilayer material sheet according to claim 7 or 8, wherein the thickness of the at least one monolayer does not exceed 10 microns.   The multilayer material sheet according to any one of the preceding claims, wherein the strength of the at least one monolayer, measured according to ASTM D885M, is at least 0.9 GPa.   The multilayer material sheet according to claim 10, wherein the strength of at least one monolayer is at least 1.5 GPa.   The multilayer material sheet according to any one of claims 1 to 11, wherein the polymer is selected from the group consisting of polyolefin, polyester, polyvinyl alcohol, polyacrylonitrile, polyamide, liquid crystal polymer, and ladder polymer.   The multilayer material sheet according to claim 12, wherein the polyolefin includes ultrahigh molecular weight polyethylene. (A) providing a plurality of stretched polymer tapes aligned such that each tape is oriented parallel to an adjacent tape, wherein the adjacent tapes do not overlap;
(B) positioning the plurality of stretched polymer tapes on a moving substrate, thereby forming a first monolayer;
(C) holding the first monolayer on the moving substrate;
(D) positioning a plurality of stretched polymer tapes on the first monolayer, thereby forming a second monolayer, wherein the direction of the second monolayer is that of the first monolayer; Forming an angle α with respect to the direction;
The method of preparing a multilayer material sheet according to any one of claims 1 to 13, further comprising: (e) compressing the stack formed in this manner and consolidating the single layer.   The method of claim 14, wherein step (a) further comprises applying a binder or bonding means to adjacent tapes.   16. The plurality of stretched polymer tapes are rewound from a rewind station, and step (d) is performed by folding the plurality of stretched polymer tapes at least partially on itself. Method.   The plurality of stretched polymer tapes are positioned such that the first single layer forms an angle β with respect to the direction of movement of the substrate, and folding is performed so that the fold extends substantially parallel to the direction of movement of the substrate. The method according to any one of claims 14 to 16.   The method of claim 17, wherein the angle β is between 40 and 50 degrees.   19. A method according to any one of claims 14-18, wherein the second monolayer is at least partially adhered to the first monolayer. (A) stacking at least two unidirectionally stretched polymer monolayers and sheets of material selected from the group consisting of ceramic, steel, aluminum, titanium, glass and graphite, or combinations thereof, the stack A plurality of stretched polymer unidirectional tapes in which the stretching directions of two consecutive monolayers are different and at least one monolayer is aligned in the same direction, wherein adjacent tapes do not overlap;
(B) A method for producing an elastic-resistant article, comprising: consolidating the stacked sheets by applying temperature and pressure.   An elastic-resistant article comprising the multilayer material sheet according to any one of claims 1 to 13.   The ballistic resistant article of claim 21 comprising at least 40 unidirectional monolayers.   23. A further sheet of inorganic material selected from the group consisting of ceramic, steel, aluminum, magnesium, titanium, nickel, chromium and iron or alloys thereof, glass and graphite, or combinations thereof. Elastic resistant article.   24. A ballistic resistant article according to claim 23, wherein the further sheet of inorganic material is positioned outside the single layer stack, at least at its impact surface.   25. A ballistic resistant article according to claim 23 or 24, wherein the thickness of the further sheet of inorganic material is at most 50 mm.   14. A tie layer exists between the further sheet of inorganic material and the material sheet according to any one of claims 1 to 13, wherein the tie layer comprises a woven or non-woven layer of inorganic fibers. Item 26. The elastic resistant article according to any one of Items 23 to 25. (A) stacking at least two unidirectionally stretched polymer monolayers and sheets of material selected from the group consisting of ceramic, steel, aluminum, titanium, glass and graphite, or combinations thereof, each A single layer includes at least one unidirectional tape, and two continuous single layers in the stack have different stretching directions and are adjacent to a substantial length of a longitudinal edge of the at least one unidirectional tape. And along which, at least one monolayer does not include an area of increased thickness;
(B) A method for producing an elastic-resistant article, comprising: consolidating the stacked sheets by applying temperature and pressure.   The multilayer material sheet according to claim 12, wherein the polymer is poly (p-phenylene terephthalamide).

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